In the prior art, there are several methods and solutions for treating dentures and other dental appliances in order to clean and remove oral deposits therefrom, and numerous cleaning solutions to be used in the methods.
For example, U.S. Pat. No. 4,806,173 (Toukan), entitled "Method of Cleaning Dental Appliances, Artificial Dentures", describes a purported method for cleaning artificial dentures by immersing the dentures in a dilute aqueous solution of carboxylic acid such as acetic, succinic, maleic, citric, mandelic or lactic acids. The concentration of the carboxylic acid in the water is in the range of 3% to 10%. The dentures are soaked overnight in the solution and then rinsed and optionally brushed before being reinserted into the wearer's mouth. The carboxylic acid thus acts on the dentures for an extended period of time (overnight) in order to effectuate the removal of oral deposits from the dentures.
U.S. Pat. No. 4,217,234 (Krisp) entitled "Denture Cleansing Tablet and Method of Manufacturing the Same" describes a purportedly fast-acting denture-cleansing tablet including certain materials, specifically aminosulfonic acid, ethylene diamine tetraacetic acid, dialkyl thiourea and a non-ionogenic fluorochemical material in an amount sufficient to achieve a pH in a 1% solution of such formulation in water of 6.3 to 6.5.
U.S. Pat. No. 4,540,505 (Eoga) and Reissue Pat. No. 32,771 issued therefrom entitled "Denture Cleaner Having Improved Dissolution Time and Clarity and Method of Preparation" describe a purported cleansing composition which is compacted into tablet form and is fact-acting. The composition comprises a phosphate salt, a perborate salt mixture including anhydrous perborate and monohydrate perborate, a polymeric fluorocarbon, and a chelating or sequestering agent in specific proportions. The composition is capable of cleansing stained surfaces of dentures in a soaking time of about 5 minutes when the tablet is dissolved in aqueous solution.
U.S. Pat. No. 4,701,233 (Eoga) entitled "Liquid Denture Cleanser Composition and Method of Application" describes a purported sprayable liquid denture cleanser composition comprising an aqueous solution of a detergent, such as a sulfonated, sulfated and sulfoacetate fatty alcohol, and a chelating agent of the amino carboxylate or organo phosphate type. The cleanser is stated to have particular application for the removal of tartar and calculus as well as stains and plaque adhering thereto.
U.S. Pat. No. 5,476,607 (Eoga et al.) entitled "Perborate: Persulfate: Protease Denture Cleanser Powder Composition" describes a purported anhydrous denture cleansing effervescent powder including anhydrous perborate, a perborate monohydrate, a lubricant and compression aid, a monopersulfate, one or more proteolytic enzymes, a sequestering agent, and optionally, excipients, builders, colors, flavors and surfactants.
With respect to patents which relate to the removal of cement from dental appliances and dental instruments, reference is made to U.S. Pat. No. 4,129,456 (Longo) entitled "Method of Removal of Dental Cement", which describes a purported method for treating dental appliances, e.g., temporary bridges and crowns, in order to remove cement from the dental appliances in which the dental appliance is placed in a glass beaker containing a full strength solvent. The full strength solvent is a solution of citric acid in a preferred concentration of 40% (corresponding to the ratio 1:2.5 of grams of citric acid to ml water), or any concentration in the range of 10% (1:10) to 89% (1:1.125). The dental appliance is left in the beaker overnight to soak in the solvent. Optionally, an ultrasonic cleaning apparatus is used during the soaking step. Thereafter, in view of the relatively high concentration of citric acid, the dental appliance must be rinsed with tap water before use by the wearer.
In general, these prior art methods do not provide a quick and easy way to clean dentures, or other removable dental appliances, in a citric acid solution so that the dentures can be worn immediately after the cleaning stage is completed without additional steps, such as a rinsing step, a brushing step and a soaking step. Rather, the prior art methods mentioned above have the disadvantages of requiring soaking of the dentures in a solution overnight, which is considered a relatively long amount of time, or using a highly concentrated citric acid solution, which is potentially hazardous and requires rinsing and possible brushing of the dentures after the cleaning stage. The use of highly concentrated citric acid solution may also require additional safety procedures such as wearing protective gloves and glasses.